The present invention pertains to processes for producing filled and/or reinforced polymer compositions and to the use of ethylenically unsaturated saccharide substances as coupling agents within such processes.
Generally speaking, filled and/or fiber reinforced polymer compositions or composites are well known items of commerce and find widespread use in the manufacture of a variety of shaped articles and other products. The polymer matrix of such filled or reinforced compositions can be either thermoplastic or thermosetting in character.
In the case of thermoplastic polymer-based systems, the filler or fiber material is generally compounded or incorporated into the polymer material via a melt processing/mixing procedure as, for example, in an extrusion compounding operation and shaped articles made from the resulting filled or reinforced thermoplastic polymer compositions can be conveniently fabricated via conventional injection molding techniques.
In the case of themosetting polymer-based compositions, the desired filler or fiber ingredient is typically admixed with or blended into one or more prepolymer ingredients (or polymer precursor materials) as, for example in a roll compounder, planetary mixer, etc. at some stage prior to the final curing or crosslinking operation employed in forming the final or finished filled or reinforced, thermoset product or article. Examples of such thermosetting polymer-based, reinforced and/or filled compositions include those which are commonly referred to in the art as "bulk molding compounds" (BMC), "sheet molding compounds" (SMC) and "reaction injection molding" (RIM) resins or systems.
In the preparation of filled and/or reinforced polymer compositions of the sort described above, it is common practice to employ a coupling agent to enhance the interfacial adhesion between the filler or fiber reinforcing material and the polymer matrix and to thereby improve the mechanical or physical properties (e.g., tensile strength, impact strength, etc.) of the resulting filled or reinforced polymer composite.
Coupling agents available and/or proposed for use to date include titanates, zirconates, silanes and methacrylato chromium complexes. While such known coupling agents have met with notable success in improving the physical properties of various composite systems, certain problems or obstacles (such as water sensitivity and/or lack of effectiveness for some classes of filler and/or polymer materials) still remain unresolved for at least some types of polymer/filler or fiber-based composite systems. Moreover, the various coupling agents available to date, for the most part, have the further disadvantage of being relatively expensive materials thereby adding significantly to the cost of composite systems in which they are employed.
As is apparent from the foregoing, there continues to be a need for the development or discovery of new and improved coupling agent materials and, particularly, for materials which are effective as coupling agents but which are relatively inexpensive compared to presently available coupling agent ingredients.